Fabrication tooling, such as welding fixtures, are often used in conjunction with a surface plate. A surface plate is a solid, flat plate used as a horizontal reference plane for precision inspection, layout, and tooling setup. The surface plate is often used as a reference plane for measurement of a workpiece placed upon or affixed to the surface plate. Consequently, a primary surface of the surface plate is a very flat planar surface, its planarity being closely controlled to facilitate accurate measurement of the workpiece.
Surface plates often include one or more datum pin holes. The datum pin holes are usually laid out in an accurate and precise geometric pattern or grid to facilitate the installation of removable attach points or supports for the tooling. For example, a welding fixture may be removably attached to a surface plate by means of a set of supports extending between the welding fixture and the surface plate.
A common problem with surface plates used in conjunction with fabrication tooling is that welding material and other debris can accumulate in the datum pin holes, rendering them unusable. Hand tools such as drills and screwdrivers may be used to repair the datum pin holes by removing the debris, but such tools are not efficient for this task. Furthermore, the datum pin holes are subject to damage by these hand tools, necessitating repair or replacement of the surface plate.